1. Field of the Invention
The present invention relates to an improvement in a suction member of a vacuum cleaner particularly useful for an upright type vacuum cleaner.
2. Description of the Background Art
Home use vacuum cleaners are mainly classified into canister type ones and upright type ones. An upright type vacuum cleaner is popular as it is easy to handle and is compact.
FIGS. 5 and 6 show the typical structure of the vacuum cleaner. FIG. 5 is a partially cut away side view and FIG. 6 is a perspective view.
A vacuum cleaner body 1 contains a dust chamber 15 and is provided with wheels 2 at the bottom. A fan motor 3 is contained at a lower portion of the body 1. A suction member 4 is rotatedly supported at a lower portion of the vacuum cleaner body 1 by a support shaft (not shown in FIG. 5: denoted by the reference numeral 5 in FIG. 1A). Inside suction member 4, a rotary brush 7 is provided, with tip ends of bristles 8 slightly protruding from a plane of a bottom plate 9-2.
A pulley is fit and fixed at one end of a rotary axis of the rotary brush 7. The rotary brush 7 is rotated by a belt 12 which is driven by a fan motor 9, so that dust in a carpet are raked, and collected to the dust chamber 15 by means of a hose 16. Here, reference numeral 22 denotes a body cover, 23 denotes a handle and 24 denotes a cord.
For cleaning a carpet by such an upright type vacuum cleaner, it is necessary to adjust the height of suction member 4 in accordance with the length of piles of the carpet. When the vacuum cleaner is used on a deep piled carpet, piles of the carpet may possibly enter too deep inside the dust suction inlet 6, and attracted by vacuum pressure, hindering movement of the suction member 4. Effective absorbing power is ensured while not damaging the carpet when the lower surface of the suction member 4 is in contact with the surface of the carpet. When the carpet and the lower surface of the suction member 4 are too heavily in contact with each other, entrance of air flow is hindered, preventing movement of dust and lowering cleaning effectiveness. Further, it becomes difficult to move the suction member 4.
In order to solve this problem, Japanese Patent Publication No. 57-21341 proposes a vacuum cleaner in which a switch lever is moved by a user so as to change the height of a forward wheel provided between the rotary brush and back wheels in the rear portion of the suction member, so that optimal height of the suction member can be selected dependent on the pile length of the carpet. Japanese Patent Publication No. 63-53809 also shows a vacuum cleaner in which height is adjusted by moving upward/downward a forward wheel attached to the suction member portion.
In the technique described in Japanese Patent Publication No. 57-21341, the height is selected by the user dependent on the pile length of the carpet, and therefore adjustment requires some skill and is troublesome. When the vacuum cleaner is operated on a deep piled carpet with the height of the forward wheel not made higher, the degree of vacuum at the suction member becomes too high and the suction member goes deep into the carpet as the lower surface of the suction member cannot be set afloat. Further, the suction member and the carpet are attracted to each other by the vacuum pressure, making it more difficult to move the suction member. This phenomenon of attraction is also experienced at the suction member of a canister type vacuum cleaner.
With regard to the rotary brush itself, the rotary brush is conventionally fabricated by attaching bristles spirally over a surface of a cylindrical roller, and its function is simply to rake out the dust at the surface of the carpet. The rotary energy of the rotary brush has been used only for rotation.